Production method for ceramic structure and production method for ceramic honeycom structure

ABSTRACT

This invention provides a production method for a ceramic structure capable of making a extrusion rate coefficient, in extruding of a ceramic structure, greater than that of prior art technologies. In a production method for a ceramic structure by the steps of mixing and kneading a ceramic batch material containing at least ceramic powder and water, extruding the mixture so kneaded, and drying and sintering a resulting extrudate, a water-insoluble liquid lubricant consisting of acyl glycerin and/or a derivative is added to the ceramic batch material.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] This invention relates to a production method for a ceramicstructure or a ceramic honeycomb structure. The method includesextrusion a ceramic material by use of a dedicated die. The inventionparticularly relates to an improvement of a extrusion rate duringextrusion.

[0003] 2. Description of the Related Art

[0004] A honeycomb structure assembled into an exhaust gas purificationapparatus of an automobile, for example, is one of the structuresproduced from ceramics such as cordierite (refer, for example, toJapanese Unexamined Patent Publication (Kokai) No. 8-11528). Thishoneycomb structure includes a cylindrical outer cladding, partitionsarranged in grid form inside the outer cladding and a large number ofcells separated by partitions and penetrating in an axial direction.

[0005] To produce this ceramic honeycomb structure, a ceramic materialcontaining ceramic powder, water, a binder and a lubricant is mixed andkneaded, extruded, and then dried and sintered.

[0006] In the honeycomb structure described above, it has been requiredto reduce the thickness of the partitions and the cell width, in orderto improve the performance of the exhaust gas purification apparatus. Tosatisfy this required, the slit width for forming the partitions must bereduced in the die used for extrusion.

[0007] However, the reduction of the slit width of the die for extrusionaffects an extrusion step and eventually, productivity of an overallproduction process. In other words, when extrusion is conducted by useof an extruder using a die that has a reduced slit width, an extrusionpressure at the same extrusion rate is higher than when the slit widthis great. Therefore, so long as the extruder having the samepressurization performance as that of existing extruders is employed,the extrusion rate unavoidably drops. The drop of this extrusion rategoverns the overall production process of the honeycomb structure, andproductivity drops.

[0008] The extrusion rate can be improved to a certain extent when abigger extruder is used to increase the pressure. In this case, however,the temperature of the resulting molding rises and the shape of theextrusion cannot be retained. Therefore, a cooler for cooling theextruder must be added or the capacity of the cooler must be increased.As a result, the setup cost increases.

[0009] When the pressurization force is excessively increased, the dieused for extrusion is broken, or extrusion defect occurs due todeflection of the die. Therefore, an increase in the pressurizationforce is limited.

[0010] For these reasons, development of a technology that can acquire ahigher extrusion rate at a lower extrusion pressure than ever has beendesired to extrude a honeycomb structure as the ceramic structuredescribed above. In other words, when a extrusion pressure and aextrusion rate are plotted on the abscissa and the ordinate,respectively, and their relation is expressed by a graph, and when thegradient (rate/pressure) is defined as “extrusion rate efficiency”,development of a technology capable of increasing this extrusion ratecoefficient has been desired.

[0011] If such a technology was available, the technology could beapplied to the production of ceramic structures, having a sheet form andvarious other forms, besides the honeycomb structure described above.

SUMMARY OF THE INVENTION

[0012] In view of the problems with the prior art technologies describedabove, the invention aims at providing a production method for a ceramicstructure capable of increasing the extrusion rate coefficient describedabove in the extrusion of ceramic structures.

[0013] A first aspect of the invention provides a production method fora ceramic structure comprising the steps of mixing and kneading aceramic material containing at least a ceramic powder and water,extruding the mixture so kneaded, and drying and sintering a extrudate,wherein a water-insoluble liquid lubricant (hereinafter merely called a“lubricant” in some cases) consisting of acyl glycerin as its maincomponent and/or its derivative is added to the ceramic batch material.

[0014] To extrusion-die a ceramic structure, it is necessary to impartplasticity to a ceramic batch material as its starting material.Therefore, water has ordinarily been added in the past to the ceramicbatch material, and a water-soluble additive such as a lubricant havinghigh compatibility with water is further added.

[0015] In the invention, a water-insoluble liquid lubricant consistingof acyl glycerin, and/or a derivative, as a main component is added tothe ceramic batch material. This is revolutionary in view of the factthat a water-soluble lubricant has been used in the past for the ceramicbatch material that is kneaded to a clay form by use of water, and theinvention employs an entirely novel ceramic batch material. In this way,the invention can make the resistance in extrusion of the ceramic batchmaterial smaller and the extrusion rate coefficient greater than whenthe water-soluble lubricant is added as in the prior art technologies.

[0016] The reason is assumed as follows. The water-insoluble liquidlubricant, that is incompatible with water but is uniformly dispersed inthe ceramic batch material kneaded into the clay form, leaches to theclay surface when a pressure is applied during extrusion, wets thefriction surfaces of a cylinder and barrel of an extruder and the die,and reduces the coefficient of friction.

[0017] This phenomenon is analogous to squeezing of a material ofvegetable oil such as soybean oil and rapeseed oil. The greater thepressure applied, the greater becomes the amount of the lubricantleached from inside the clay. Therefore, even when the precessurelocally increases, a necessary amount of the lubricant leachesconcentratedly to that portion and reduces the coefficient of friction.

[0018] In contrast, water-soluble lubricants according to the prior arthave high affinity with water and are bonded to the ceramic powermaterial together with water. Therefore, even when the pressure isapplied during extrusion, the lubricants do not leach to the claysurface. Therefore, only the limited amount of the water-solublelubricants existing on the clay surface can contribute to lubricationperformance. Even when a high pressure is locally applied, theselubricants cannot be concentrated on that portion, and cannot reduce thecoefficient of friction, either.

[0019] The lubricant consisting of acyl glycerin and/or its derivativeamong the water-insoluble liquid lubricants can secure a relativelylarge gap between the ceramic raw material and the friction surface ofthe die, though the reason has not entirely been clarified. It isassumed that the greater the adsorption force of the lubricant to thedie, the smaller becomes the coefficient of friction.

[0020] The invention can make the extrusion rate coefficient, describedabove, in extrusion of the ceramic Structure greater than in the priorart technologies. Therefore, the invention can suppress a drop in therate when a ceramic structure having a shape that involves a large dieresistance during extrusion is extruded. In consequence, the inventioncan improve productivity while keeping the quality of the ceramicstructure and its shape retainability.

[0021] A second aspect of the invention provides a production method ofa ceramic honeycomb structure having partitions arranged in a honeycombshape, comprising the steps of mixing and kneading a ceramic batchmaterial containing at least ceramic powder, water, a binder, extrudingthe mixture so kneaded, and drying and sintering a extrudate, wherein awater-insoluble liquid lubricant that is a water-insoluble liquid at atemperature of extrusion is added to the ceramic batch material.

[0022] When a ceramic honeycomb structure is extrusion, water-containingminerals such as talc, kaolin, and so forth, are used as the mainmaterial of the ceramic batch material. Therefore, large quantities ofwater having high compatibility with them have been used in the past.Therefore, it has been believed that additives such as a lubricant mustbe water-soluble.

[0023] In the second invention, the water-insoluble liquid lubricantthat is a water-insoluble liquid at a temperature of extrusion is addedto the ceramic batch material. This is extremely revolutionary in theproduction of the ceramic honeycomb structure because the water-solublelubricant has been employed in the past. In other words, the inventionuses a ceramic batch material having an entirely novel construction. Incomparison with the case where the water-soluble lubricant is added asin the prior art technologies, the resistance when extruding the ceramichoneycomb structure by extruding the ceramic batch material can bereduced, and the extrusion rate coefficient can be increased.

[0024] Because the second invention can make the extrusion ratecoefficient greater in extrusion of the ceramic honeycomb structuregreater than in the prior art technologies, the drop of the extrusionrate can be suppressed when a ceramic honeycomb structure, having ashape that has a large die resistance in extruding, is extruded. Thesecond invention can further suppress die cracking resulting from theincrease of the pressure and extrusion defect resulting from diedeflection. For these reasons, the second invention can improveproductivity while keeping the quality of the ceramic honeycombstructure and its shape retainability.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is an explanatory view showing a construction of anextruder in Example 1;

[0026]FIG. 2 is an explanatory view showing a construction of ahoneycomb structure in Example 1;

[0027]FIG. 3 is an explanatory view showing a clearance between aceramic batch material and a friction surface of a die when usingpolyoxyethylene polyoxypropylene monobutylether (PPBE) as an example ofexisting lubricants;

[0028]FIG. 4 is an explanatory view showing a clearance between theceramic batch material and the friction surface of a die when rapeseedoil (Canola oil) (triacyl glycerin) is used in Example 1;

[0029]FIG. 5 is an explanatory view showing a relation between aextrusion pressure and a extrusion rate in Example 2;

[0030]FIG. 6 is an explanatory view showing a relation between anaddition amount of rapeseed oil and a extrusion rate ratio in Example 3;

[0031]FIG. 7 is an explanatory view showing a relation between aextrusion pressure and a extrusion rate in Example 4;

[0032]FIG. 8 is an explanatory view showing a relation between thenumber of revolutions of a motor and a extrusion rate in Example 5;

[0033]FIG. 9 is an explanatory view showing a relation between thenumber of revolutions of a motor and a motor current in Example 5;

[0034]FIG. 10 is an explanatory view showing a relation between a liquidratio in a ceramic batch material and hardness in Example 6;

[0035]FIG. 11 is an explanatory view showing a relation between awater-insoluble liquid lubricant and a kinematic viscosity (cSt) inExample 6;

[0036]FIG. 12 is an explanatory view showing experimental points of alubricant content and a water content (moisture ratio) with respect to amatrix in Example 7; and

[0037]FIG. 13 is an explanatory view showing an optimum range oflubricant content and water content (moisture ratio) in a matrix inExample 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The first invention described above can use a water-insolubleliquid lubricant consisting of acyl glycerin, and/or a derivative, as amain component. The term “liquid lubricant” herein used excludes thosegrease-like liquid lubricants that have an extremely high viscosity atnormal temperature.

[0039] The water-insoluble liquid lubricant consisting of acyl glycerin,and/or a derivative, as the main component preferably has a viscosity of15 to 45 cp at 50° C. In this case, handling of the water-insolubleliquid lubricant becomes easier when an automatic line is set up. Whenthe viscosity is less than 15 cp, the viscosity is so low that asufficient effect cannot be acquired in extrusion at a high pressure.When the viscosity exceeds 45 cp, on the other hand, the viscosity is sohigh that an extrusion rate cannot be improved.

[0040] To measure the viscosity (cp) described above, rotary viscometersknown generally such as a B type, a C type, a BH type, an E type, and soforth, can be employed for the measurement.

[0041] Acyl glycerin is called “acyl glycerol” according to the IUPACnomenclature, and includes monoacyl glycerin, diacyl glycerin andtriacyl glycerin. Triacyl glycerin among them is a main component ofnatural fat. It is expressed by a chemical formula in which threealiphatic acids are bonded with one glycerin:

[0042] (where each of R₁, R₂ and R₃ is an alkyl group of an aliphaticacid).

[0043] The aliphatic acids R₁, R₂ and R₃ in the chemical formula givenabove include various kinds. Examples of the water-insoluble liquidlubricant consisting of triacyl glycerin, and/or a derivative, as itsmain component are various vegetable oil such as rapeseed oil, soybeanoil, sunflower oil, cotton seed oil, and so forth.

[0044] Preferably, 2.0 to 8.0 wt % (to be added) of methyl cellulose onthe basis of 100 wt % of ceramic powder is added to the ceramic batchmaterial. Methyl cellulose increases plasticity, improves shaperetainability when extrusion is conducted, and improves dry strength ofa dried ceramic structure. When the addition amount of methyl celluloseis les than 2.0 wt % (to be added), an improvement effect of plasticityand bonding power during drying due to its addition cannot be expected.When the addition amount of methyl cellulose exceeds 8.0 wt % (to beadded), on the other hand, a problem occurs that volume shrinkagebecomes excessively great after sintering.

[0045] In the invention, when the amount of ceramic powder is 100 wt %as the unit of the addition amount, the amount of the component to beadded to ceramic powder is expressed as wt % (to be added) and when theoverall ceramic bath is expressed as 100 wt %, the component containedin the batch material is expressed by wt % (to be contained).

[0046] The water-insoluble liquid lubricant consists of triacyl glycerinas the main component. The addition amount of the water-insoluble liquidlubricant is preferably at least 0.5 wt % (to be added) on the basis of100 wt % of ceramic powder. When the water-insoluble liquid lubricantconsisting of triacyl glycerin as the main component is used, the effectof improving the extrusion rate coefficient brought forth by theaddition of the water-insoluble liquid lubricant is small if theaddition amount of the water-insoluble liquid lubricant is less than 0.5wt % (to be added) There is no upper limit to the addition amount of thewater-insoluble liquid lubricant from the aspect of the improvement ofthe extrusion rate coefficient, the addition amount is preferablylimited from the aspects of saturation of the addition effect and theincrease of the cost.

[0047] The main component of the aliphatic acid constituting triacylglycerin described above is preferably an aliphatic acid having 18carbon atoms. Concrete examples are stearic acid, oleic acid, linolicacid, linolenic acid, elaidic acid, cis-vaccenic acid, vaccenic acid andother aliphatic acids- Triacyl glycerin constituted by these C18aliphatic acids is liquid at normal temperature, has a suitableviscosity and is most suitable as the water-insoluble liquid lubricant.

[0048] A saponification value of triacyl glycerin is preferably notgreater than 200. In this case, the effect of improving the extrusionrate coefficient can be sufficiently acquired.

[0049] Next, in the production method of the ceramic honeycomb structureaccording to the second invention, the water-insoluble liquid lubricantthat is a water-insoluble liquid at the temperature of extrusion isadded to the ceramic batch material.

[0050] In the case of the ceramic honeycomb structure, a binder such asmethyl cellulose is generally added to the batch material to impartplasticity and to obtain dry strength. When the temperature is too high,in this case, the resulting extrusion becomes so soft that shaperetainability cannot be secured. Therefore, extrusion is carried outwhile the temperature of the material (at the time of extrusion) iscontrolled to about 10 to about 30° C. with a center temperature atabout 20° C.

[0051] Therefore, the water-insoluble liquid lubricant suitable for thispurpose preferably has a kinematic viscosity of 30 cSt to 120 cSt at 20°C.

[0052] Therefore, a sufficient effect can be obtained when the ceramichoneycomb structure is extruded while the material temperature iscontrolled to 10 to 30° C., too.

[0053] Incidentally, the kinematic viscosity described above may belongto the following four viscosity grades stipulated in ISO viscosityclassification for industrial lubricant oil (ISO 3448-1975 and JIS K2001“Viscosity Classification of Industrial Lubricant Oil” appliedcorrespondingly to the former), that is, ISO VG22, ISO VG32, ISO VG46and ISO VG68.

[0054] The sum of water and the water-insoluble liquid lubricantcontained in the ceramic batch material is preferably 18.0 to 24.5 wt %(to be contained) on the basis of 100 wt % of the total ceramic batchmaterial.

[0055] When the sum of water and the water-insoluble liquid lubricantcontained in the ceramic batch material exceeds 24.5 wt % (to becontained), the raw material becomes so soft that the ceramic honeycombstructure undergoes deformation due to its own weight and cannot retainthe shape after extruding even when the material temperature isregulated.

[0056] When the sum of water and the water-insoluble liquid lubricantcontained in the ceramic batch material is smaller than 18.0 wt % (to becontained), the viscosity of the material becomes so high that theextrusion pressure exceeds the die strength, or the ceramic batchmaterial becomes powdery and dusty with the result that plasticizationcannot be attained (the material does not become clay-like) andextruding becomes substantially impossible.

[0057] When the thickness of partitions of the ceramic honeycombstructure is smaller than 150 μm, that is, when extrusion is carried outby use of a die having a slit width of smaller than 150 μm, the sum ofwater and the water-insoluble liquid lubricant is preferably 20.0 to22.5 wt % (to be contained) on the basis of 100 wt % of the overallceramic batch material as will be later described. Shape retainabilityis of importance in a thin ceramic honeycomb structure, and to retainthe shape, the sum of the contents is more preferably not greater than22.5 wt % (to be contained) Since the extrusion pressure becomes greaterin the thin ceramic honeycomb structure, the sum of the content is morepreferably at least 20.0 wt % (to be contained) to obtain an excellentextrusion condition.

[0058] In the second invention, the binder described above is methylcellulose, and the content of the binder is preferably 2.0 to 8.0 wt %(to be added) when the content of ceramic powder is 100 wt %. The reasonfor limitation of the methyl cellulose content in this case is the sameas that of the first invention.

[0059] The ceramic honeycomb structure described above has partitionsarranged in the honeycomb shape. Therefore, it has large resistanceparticularly when passing through the die, and the extrusion ratecoefficient is likely to become small. In this sense, the application ofthe invention is extremely effective.

[0060] The thickness of the partitions is preferably not greater than150 μm. In this case, because the resistance becomes great when theceramic honeycomb structure passes through the die, and the applicationof the invention is further effective.

[0061] The honeycomb structure is preferably extrusion-molded by use ofa die having slits for forming the partitions described above, and awidth of the slit is preferably not greater than 150 μm. When the slitwidth of the die for extruding the honeycomb structure is not greaterthan 150 μm in the honeycomb structure, the extrusion rate coefficientdrops particularly at the time of extrusion. Therefore, when the slitwidth is not greater than 150 μm in the honeycomb structure, too, theapplication of the invention is further effective.

[0062] In the second invention, too, the water-insoluble liquidlubricant is triacyl glycerin and when the amount of ceramic powder is100 wt %, the addition amount of the water insoluble liquid lubricant ispreferably 1.0 to 8.0 wt % (to be added).

[0063] When the addition amount of the water-insoluble liquid lubricantexceeds 8.0 wt % (to be added) in the case of a ceramic honeycombstructure having a complicated shape, large amounts of oil are burnt andscattered during a degreasing process at the time of sintering, andsintering cracks are likely to occur. When the amount is less than 1.0wt % (to be added), the remarkable effect of improving the extrusionrate cannot be obtained in comparison with the existing level.Therefore, the addition amount of the water-insoluble liquid lubricantis preferably 1.0 to 8.0 wt % (to be added).

[0064] In the second invention, too, the main component of the aliphaticacid constituting triacyl glycerin described above is preferably analiphatic acid having 18 carbon atoms in the same way as in the firstinvention.

[0065] In the second invention, too, the saponification value of triacylglycerin is preferably not greater than 200 in the same way as in thefirst invention

EXAMPLE 1

[0066] A production method of a ceramic structure according to thisexample will be explained with reference to FIGS. 1 to 4.

[0067] In a method of producing a ceramic structure 8 by the steps ofmixing and kneading a ceramic batch material 88 containing at leastceramic powder and water, extruding the mixture, and drying andsintering the resulting extrudate, this example added a water-insolubleliquid lubricant consisting of acyl glycerin and/or its derivative as amain component to the ceramic batch material 88.

[0068] Hereinafter, an explanation will be given in detail.

[0069] This example produced a honeycomb structure including an outercladding 81, partitions 82 arranged in a grid form inside the outercladding 81 and a large number of cells 80 separated by the partitions82 and penetrating in an axial direction, and consisting of cordieriteas the main component.

[0070] First, talc, kaolin, alumina and aluminum hydroxide powder thatwere components capable of changing to cordierite after sintering wereused as ceramic powder that constituted the ceramic batch material 88described above. A water-insoluble liquid lubricant consisting of methylcellulose, water and acyl glycerin and/or its derivative as the maincomponent was added to the powder mixture to form the ceramic batchmaterial 88.

[0071] Rapeseed oil consisting of triacyl glycerin as the maincomponent, more concretely rapeseed oil containing 97% of triacylglycerin, 0-8% of diacyl glycerin and 0.1% of monoacyl glycerin byweight ratio, was used as the water-insoluble liquid lubricantconsisting of acyl glycerin and/or its derivative as the main component.

[0072] The aliphatic acid composition (mol %) consists of C_(16.0)=4.0%,C_(18.0)=1.8%, C_(18.1)=57.8%, C_(18.2)=21.8%, C_(18.3)=11.2%,C_(20.1)=1.9% and C_(22.1)=1.0%. Here, symbol C represents carbon,symbol a in a:b as the suffix to C represents the number of carbon atomsand b represents the number of double bonds.

[0073] Next, the ceramic batch material 88 was kneaded in a kneader 3and was extruded by use of a screw type extruder 1 as shown in FIG. 1.Each of the extruder 1 and the kneader 3 included inside a cylindricalframe 11, 31 a screw 15, 35 having a screw plate 150, 350 that washelically wound. The crew 15, 35 was driven for rotation by a motor 17,37 connected to its rear end.

[0074] A material charging hole 39 was provided to the upper part of theframe 31 of the kneader, and the ceramic batch material 88 was chargedthrough this charging hole 39. The kneaded ceramic batch material 88 wasextruded from a distal end portion 38 of the kneader 31 and was thencharged into a material charging hole 19 of the extruder 1. The materialcharging portion to the extruder 1 was kept as a whole under vacuum by avacuum pump 195 to suppress entrapment of the ceramic batch materialinto air.

[0075] A die 2 for shaping was arranged at the distal end of theextruder 1. The die 2 had grid-like slits 20 corresponding to the shapeof the partitions 82 of the honeycomb structure 8 to be produced.

[0076] To conduct extrusion, after being kneaded by the kneader 3, theceramic batch material 88 was charged into the extruder 1, was movedforth by the revolution of the screw 15 and was thereafter extruded fromthe die 2. In this way, the honeycomb structure 8 was extruded andextruded.

[0077] The honeycomb structure 8 so extruded was serially cut into adesired length and was passed through subsequent drying and sinteringsteps to give complete products.

[0078] In this embodiment, rapeseed oil as the water-insoluble liquidlubricant consisting of triacyl glycerin as described above was added tothe ceramic batch material 88. Therefore, in comparison with the casewhere a conventional lubricant was added, the extrusion rate coefficientin extrusion could be drastically improved and presumably for thefollowing reason.

[0079] The water-insoluble liquid lubricant such as triacyl glycerin wasnot dissolved in water but was dispersed in the ceramic batch material.Therefore, when the pressure was applied during extrusion, the lubricantleached to the clay surface, lubricated the cylinder, the barrel and thefriction surface of the die and could thus decrease the coefficient offriction. The greater the pressure applied in this case, the greaterbecame the amount of the lubricant leaching from inside the clay.Consequently, even when the pressure locally increased, a necessaryamount of lubricant was concentratedly supplied to that portion, and thecoefficient of friction could be efficiently lowered.

[0080] In contrast, a water-soluble lubricant was highly hydrophilic andwas strongly bonded to the ceramic material as an aqueous solution.Therefore, even when the pressure was applied during extrusion, thelubricant did not leach to the clay surface.

[0081] In consequence, only a very small amount of the water-solublelubricant existing on the clay surface contributed to lubricationperformance. Even when a high pressure was locally applied, thelubricant did not concentrate on that portion and the frictional forcereducing effect could not presumably operate sufficiently.

[0082] Synthetic lubricants well known in the past includespolyoxyethylene-polyoxypropylene-monobuthylether (trade name: “Uniloob”)expressed by the following formula:

[0083] This synthetic lubricant became water-soluble and water-insolubledepending on a polymerization ratio of propylene oxide and ethyleneoxide. Since this lubricant was used in combination with water in thefield of ceramics, it was generally used while the ratio of ethylene tooxide was set to 40% or more. In this case, the oxygen ion (O⁻) ofethylene oxide was adsorbed to the iron ion (Fe⁺) of the die 2, forexample, between the die 2 and the boundary 89 surface of the solidcontent of the ceramic batch material as shown in FIG. 3. Therefore,though PPBE described above had a relatively large molecular weight andan elongated molecule, the elongated molecule did not remain upright anda sufficient distance could not be secured between the die 2 and theboundary surface 89 As the adsorption force of the oxygen ion (O⁻) wasrelatively small, the water-soluble lubricant was likely to peel fromthe die 2.

[0084] On the other hand, the water-insoluble liquid lubricantconsisting of triacyl glycerin as the main component in this examplecould be arranged between the die 2 and the boundary surface 89 of thesolid content of the ceramic batch material while the molecule of thealiphatic acid remained upright as shown in FIG. 4. Further, the acylglycerin had a carbonyl group (COO⁻) and exhibited a stronger adsorptionforce to the iron ion (Fe⁺) than to the oxygen ion (O⁻). Therefore, thewater-insoluble liquid lubricant (rapeseed oil) consisting of triacylglycerin as the main component of this example was more difficult topeel from the die 2 than the conventional water-soluble lubricant.

[0085] Presumably because the water-insoluble liquid lubricantconsisting of triacyl glycerin as the main component was used as in thisexample, lubrication performance could be improved and the extrusionrate coefficient could be increased.

EXAMPLE 2

[0086] To further clarify the effect of Example 1, this exampleconducted experiments by comparing the case where PPBE (C1) was used asthe conventional water-soluble lubricant with the cases wherewater-insoluble liquid lubricants consisting of four kinds of acylglycerin as the main components were used.

[0087] Rapeseed oil (E1), soybean oil (E2), safflower oil (E3) andlinseed oil (E4) consisting of triacyl glycerin as the main componentwere used as the water-insoluble liquid lubricants consisting of acylglycerin as the main component.

[0088] A batch type kneader was used as a kneader, a screw type extruderfor an experimental use was used as a extruding machine, and a diehaving a slit width of 150 μm and 400 mesh (400 cells/in.²) was used asa die. Honeycomb structures having an outer diameter of Φ500 mm wereextruded.

[0089] To prepare a ceramic batch material, 5 wt % (to be added) ofmethyl cellulose, 25.9 wt % (to be added) of water and 2.7 wt % (to beadded) of various lubricants on the basis of 100 wt % of ceramic powderwere added to a ceramic powder.

[0090] The extrusion rate relative to the extrusion pressure inextrusion by the screw extruder described above was measured.

[0091]FIG. 5 shows the measurement result. In the diagram, the abscissarepresents the extrusion pressure (MPa/cm²) and the ordinate does theextrusion rate (m/min). Symbols C1 and E1 to E4 respectively representthe results when the lubricants (C and E1 to E4) were used.

[0092] As can be understood from the diagram, the extrusion rates at thesame extrusion pressure could be much more improved when thewater-insoluble liquid lubricants (E1 to E4) consisting of triacylglycerin as the main component were used than when the conventionalwater-soluble lubricant (C1) was used. In other words, the extrusionrate coefficient could be improved.

[0093] It could be understood from this result that the extrusion ratecoefficient could be drastically increased in extrusion of the honeycombstructure when the lubricant consisting of triacyl glycerin was used asthe water-insoluble liquid lubricant.

EXAMPLE 3

[0094] This example used rapeseed oil as a typical example of thewater-insoluble liquid lubricant consisting of acyl glycerin as the maincomponent, and a test was carried out to determine an optimum range ofits addition amount.

[0095] The test condition was as follows.

[0096] First, a ceramic powder that had the same composition as inExample 1, and methyl cellulose, water and rapeseed oil were added to 3kg in total of ceramic powder. The addition amount of methyl cellulosewas fixed at 5 wt % (to be added) on the basis of 100 wt % of ceramicpowder, and the addition amount of water was fixed at 26 wt % (to beadded) on the basis of 100 wt % of ceramic powder. The addition amountof rapeseed oil was changed within a range of 0.5 to 10.0 wt % (to beadded) on the basis of 100 wt % of ceramic powder For comparison, a casewhere rapeseed oil was not added at all was also tested.

[0097] A batch type kneader was used as a kneader for kneading theceramic batch material, and an FM-30 vacuum extruder, a product ofMiyazaki Steel Co., was used as a extruding machine. A die having a slitwidth of 150 m and the number of cells of 400 cells/in.² was used.

[0098] Ceramic batch materials having mutually different additionamounts of rapeseed oil were used and each extrusion rate with respectto a extrusion pressure was measured to determine the extrusion ratecoefficient for each addition amount of rapeseed oil. The extrusion ratecoefficient when rapeseed oil was not added was set to 1, and a ratio tothis value was determined as a extrusion rate ratio.

[0099]FIG. 6 shows the result. In this diagram, the abscissa representsthe addition amount (wt % to be added) of rapeseed oil, and the ordinatedoes the extrusion rate ratio. The result is represented as E5.

[0100] In the diagram, the extrusion rate ratio when 2-7 wt % (to beadded) of PPBE as a conventional water-soluble lubricant was added wasalso plotted as C1. It could be understood by comparing them that whenthe addition amount of rapeseed oil was at least 1.0 wt % (to be added),a extrusion rate coefficient higher than that of the prior art could besufficiently obtained.

[0101] It was thus clarified that when the addition amount of rapeseedoil was at least 0.5 wt % (to be added), the effect of improving theextrusion rate coefficient could be obtained and when it was at least1.0 wt % (to be added), the extrusion rate coefficient higher than thatof the prior art could be obtained.

[0102] On the other hand, when the addition amount of rapeseed oil wasincreased, the ceramic batch material became so soft, as a whole, thatshape retainability of the extrudate became lower. In this example, whenthe addition amount of rapeseed oil exceeded 10.0 wt % (to be added),shape retainability dropped and a desired honeycomb shape could not beobtained.

[0103] Therefore, it could be concluded that the addition amount ofrapeseed oil as the lubricant consisting of acyl glycerin as the maincomponent was preferably less than 10.0 wt % (to be added).

[0104] From the aspect of the cost, the addition amount of rapeseed oilwas preferably small. To obtain reliable improvement of the extrusionrate coefficient and to reduce the cost, therefore, the addition amountwas preferably not greater than 8.0 wt % (to be added).

[0105] Since the hardness of the ceramic batch material could beregulated by the addition amount of water, a ceramic batch materialhaving suitable hardness could be obtained by adjusting the additionamount of rapeseed oil and the addition amount of water.

[0106] Though this example represented the case where rapeseed oil wasused as the lubricant, substantially similar effects could be obtainedwhen other lubricants consisting of triacyl glycerin as the maincomponent were used.

[0107] It was of course possible to add the conventional water-solublelubricant to the lubricant consisting of acyl glycerin as the maincomponent. The water-soluble lubricant hardly exhibited the effect ofimproving the extrusion rate coefficient in this case, but provided alubrication effect with respect to other equipment such as a water pump.

EXAMPLE 4

[0108] In this example, an extremely thin honeycomb structure having apartition thickness of 3 mil (76.2 μm) was actually extruded, and theeffect of the lubricant consisting of acyl glycerin as the maincomponent was confirmed.

[0109] In other words, the die used for extrusion in this example had aslit width of 3 mil (76.2 μm) and the number of cells of 400 cells/in.²,and a honeycomb structure having an outer diameter of (Φ107 mm wasmolded.

[0110] The composition of the ceramic batch material was fundamentallythe same as that of Example 3, and the addition amount of rapeseed oilas the lubricant was fixed at 3 wt % (to be added).

[0111] For comparison, a test was also carried out by the use of aceramic batch material containing 3 wt % (to be added) of PPBE as thewater-soluble lubricant.

[0112] A large-scale screw type vacuum extruder for a production plant(not shown) was used as a kneader and a extruding machine.

[0113]FIG. 7 shows the test result. In the diagram, the abscissarepresents the extrusion pressure (MPa/cm²) and the ordinate representsthe extrusion rate (m/min). Symbol E6 represents the case of theaddition of rapeseed oil and C2 does the case where PPBE was added.

[0114] It can be understood from the diagram that when rapeseed oil asthe lubricant consisting of acyl glycerin as the main component wasused, the extrusion rate, that is, the extrusion rate coefficient, couldbe drastically improved at the same extrusion pressure in comparisonwith the prior art when the honeycomb structure having extremely thinpartitions of 76.2 μm was extruded.

EXAMPLE 5

[0115] This example used linseed oil as the lubricant consisting of acylglycerin as the main component, and actually extruded a honeycombstructure having a partition thickness of 4 mils (101.6 μm), the numberof cells of 600 cells/in.² and an outer shape of Φ120 mm. The result wascompared with the case where the water-soluble lubricant (PPBE) was usedin the same way as in Example 4.

[0116] The addition amount of linseed oil was 3 wt % (to be added). Therest were the same as in Example 4.

[0117] In this example, extrusion was carried out while the number ofrevolutions of a motor for turning a screw shaft of a screw typeextruder and a motor current were respectively measured to examine therelations between these values and the extrusion rate.

[0118]FIGS. 8 and 9 show the test result. In FIG. 8, the abscissarepresents the number of revolutions of the motor (rpm) and the ordinaterepresents the extrusion rate (m/min). In FIG. 9, the abscissarepresents the number of revolutions of the motor (rpm) and the ordinaterepresents the motor current (A). Symbol E7 represents the case wherelinseed oil was used and C3 represents the case where PPBE was used.

[0119] It can be understood from FIG. 8 that when the number ofrevolutions of the extrusion screw was the same, the extrusion rate ofthe case (E6) where linseed oil was used became substantially twice atthe same number of revolutions in comparison with the extrusion rate ofthe case (C3) where the water-soluble lubricant was used.

[0120] It could be understood from FIG. 9 that the motor current valueat the same number of revolutions became lower in the case (E7) wherelinseed oil was used than in the case (C3) where PPBE was used, and themotor load at the same number of revolutions dropped. This waspresumably because the friction between the ceramic batch material andthe die decreased when linseed oil was used as the lubricant consistingof acyl glycerin as the main component. Further, when the lubricantconsisting of acyl glycerin as the main component was used, life of thedie could be extended due to the decrease of the friction of the die.

EXAMPLE 6

[0121] This example used rapeseed oil, linseed oil and soybean oil asthe water-insoluble liquid lubricants consisting of triacyl glycerin asthe main component. Each ceramic batch material for a ceramic honeycombstructure containing the lubricant in a blend ratio tabulated in Tables1 to 3 was kneaded in a batch type kneader. The clay hardness(plasticity) was examined, and the ceramic honeycomb structures wereextruded by use of a vacuum extruder in the same way as in Example 3 toevaluate extrudability and the extrusion rate.

[0122] Tables 1 to 3 and FIG. 10 illustrate the evaluation results. FIG.10 shows the clay hardness (plasticity) with respect to the proportionof the total weight of water and the lubricant (hereinafter called“liquid ratio”; unit=wt % (to be added) in the total weight of thematerial.

[0123] Here, clay hardness (plasticity: workability index, stipulated informer JIS P2574 abandoned in 1998) is the value measured by use of apencil-shaped spring type penetrometer ordinarily used in this field.When a distal end of the penetrometer is inserted into the clay, ahigher numerical value represents a higher hardness and a smallernumerical value represents a lower hardness.

[0124] It could be understood from FIG. 10 that in all the cases ofrapeseed oil, linseed oil and soybean oil, the clay hardness becamehigher as the sum of the lubricant and water, that is, the liquid ratio,became smaller (plasticity coefficient became greater) irrespective ofthe ratio of the lubricant and water, and the clay hardness became loweras the liquid ratio became greater (plasticity coefficient becamesmall), and that they had a strong correlation. Therefore, when thelubricant consisting of triacyl glycerin as the main component was addedto the raw material of the ceramic honeycomb structure, the clayhardness (plasticity) could be easily regulated by regulating theaddition amount of water in accordance with the necessary amount of thelubricant. It was estimated that the extrudability of the ceramichoneycomb structure could be easily regulated.

[0125] In this example, a relatively high extrudability could beobtained at a liquid ratio of 18 to 24.5 wt % (to be contained) and ahardness (plasticity coefficient) of 9 to 11 and preferably a liquidratio of 20 to 22.5 wt % (to be contained) and a hardness of 9.6 to10.7. Incidentally, the inclination of the relation between the clayhardness (plasticity coefficient) and the liquid ratio became somewhatdifferent depending on the kind of the lubricant presumably because ofthe difference of the viscosity of the lubricant at the measurementtemperature.

[0126] For reference, the relation between the temperature of thewater-insoluble liquid lubricant used for the test and the kinematicviscosity was examined in this example. Incidentally, the kinematicviscosity (kinematic viscoelasticity) is the quotient obtained bydividing the viscosity (coefficient of viscosity) by the density (ρ) ofthe liquid. Its unit is mm²/s or cSt, and 1 mm₂/s=1 cSt. Though Pa·s isused in due form as the unit of viscosity (coefficient of viscosity), cP(centi-poise) is customarily used, and 1 Pa·s=1×10³ cP.

[0127] In this example, the kinematic viscosity was measured by use ofan Ostwald viscometer as a kind of capillary viscometer. FIG. 11 showsthe measurement result. In the diagram, the abscissa represents thetemperature and the ordinate represents the kinematic viscosity (cSt).

[0128] It could be understood from the diagram that the kinematicviscosity at 20° C. was 43.1 cSt for the soybean oil, 86.8 cSt forrapeseed oil and 45.8 cSt for linseed oil. The kinematic viscosity at40° C. was 27.1 cSt for soybean oil, 47.6 cSt for rapeseed oil and 28.1cSt for linseed oil.

[0129] For reference, the result of measurement obtained by using an Etype viscometer and a BH type viscometer (products of Tokyo Keiki Co.)as a kind of rotary viscometer is also shown.

[0130] The measurement result by the E type viscometer at 50° C. was22.0 cp for soybean oil, 24.2 cp for rapeseed oil and 18.2 cp forlinseed oil.

[0131] The measurement result by the BH type viscometer was availableonly for linseed oil, and was 100 cp at 10° C., 60 cp at 25° C. and 45cp at 33° C. TABLE 1 lubricant: linseed oil ceramic batch materialmethyl liquid cellulose lubricant water ratio evaluation result ceramicpowder wt % wt % wt % wt % extrusion Experiment weight weight (to beweight (to be weight (to be (to be hard- rate No. (g) wt % (g) added)(g) added) (g) added) contained) ness extrudability ratio 1 3000 100 1505.0 30 1.0 660 22.0 18.0 12.4 X 1.38 2 3000 100 150 5.0 90 3.0 780 26.021.6 9.9 ◯ 1.90 3 3000 100 150 5.0 150  5.0 900 30.0 25.0 7.5 X 1.93 43000 100 150 5.0 30 1.0 780 26.0 20.5 10.7 ◯ 1.40 5 3000 100 150 5.0 903.0 900 30.0 23.9 8.3 Δ 1.85 6 3000 100 150 5.0 150  5.0 660 22.0 20.510.7 ◯ 1.95 7 3000 100 150 5.0 30 1.0 900 30.0 22.8 9.1 Δ 1.35 8 3000100 150 5.0 90 3.0 660 22.0 19.2 11.6 Δ 1.92 9 3000 100 150 5.0 150  5.0780 26.0 22.8 9.1 Δ 1.98

[0132] TABLE 2 lubricant: rapeseed oil ceramic batch material methylliquid cellulose lubricant water ratio evaluation result ceramic powderwt % wt % wt % wt % extrusion Experiment weight weight (to be weight (tobe weight (to be (to be hard- rate No. (g) wt % (g) added) (g) added)(g) added) contained) ness extrudability ratio 1 3000 100 150 5.0 30 1.0660 22.0 18.0 11.8 X 1.48 2 3000 100 150 5.0 90 3.0 780 26.0 21.6 10.1 ◯1.97 3 3000 100 150 5.0 150  5.0 900 30.0 25.0 8.6 X 1.98 4 3000 100 1505.0 30 1.0 780 26.0 20.5 10.7 ◯ 1.44 5 3000 100 150 5.0 90 3.0 900 30.023.9 9.1 Δ 1.95 6 3000 100 150 5.0 150  5.0 660 22.0 20.5 10.7 ◯ 2.05 73000 100 150 5.0 30 1.0 900 30.0 22.8 9.6 Δ 1.43 8 3000 100 150 5.0 903.0 660 22.0 19.2 11.2 Δ 1.92 9 3000 100 150 5.0 150  5.0 780 26.0 22.89.6 Δ 1.98

[0133] TABLE 3 lubricant: soybean oil ceramic batch material methylliquid cellulose lubricant water ratio evaluation result ceramic powderwt % wt % wt % wt % extrusion Experiment weight weight (to be weight (tobe weight (to be (to be hard- rate No. (g) wt % (g) added) (g) added)(g) added) contained) ness extrudability ratio 1 3000 100 150 5.0 30 1.0660 22.0 18.0 11.0 X 1.38 2 3000 100 150 5.0 90 3.0 780 26.0 21.6 9.8 ◯1.86 3 3000 100 150 5.0 150  5.0 900 30.0 25.0 8.8 X 1.90 4 3000 100 1505.0 30 1.0 780 26.0 20.5 10.2 ◯ 1.39 5 3000 100 150 5.0 90 3.0 900 30.023.9 9.1 Δ 1.87 6 3000 100 150 5.0 150  5.0 660 22.0 20.5 10.2 ◯ 1.95 73000 100 150 5.0 30 1.0 900 30.0 22.8 9.5 Δ 1.36 8 3000 100 150 5.0 903.0 660 22.0 19.2 10.6 ◯ 1.96 9 3000 100 150 5.0 150  5.0 780 26.0 22.89.5 Δ 1.92

EXAMPLE 7:

[0134] In this example, the liquid ratio was fixed at 21.35 wt % (to becontained) by adjusting the water content on the basis of the result ofExample 6, rapeseed oil was used as the lubricant in the same way as inExample 3, and a extruding test was carried out by changing the additionamount of the lubricant within a range of 1 to 10 wt % (to be added).

[0135] When the addition amount of the lubricant was 10 wt % (to beadded) in Example 3, shape retainability could not be secured and theresulting extrudate underwent deformation. In this example, theextruding test was carried out at a constant liquid ratio by adjustingthe water content. Therefore, extrudability hardly changed even when theaddition amount of the lubricant was changed from 1 to 10 wt % (to beadded), and an excellent extrusion could be obtained even at 10 wt % (tobe added). Moreover, the extrusion rate could be increased when theaddition amount of the lubricant was increased in the same way as inExample 3, and its effect could thus be confirmed.

[0136] It was found, however, that when the extrudates were sintered,the sintering shrinkage ratio became greater in extrudates having agreater addition amount of the lubricant, and sintering cracks becamelikely to occur when the addition amount exceeded 8 wt % (to be added).

[0137] Therefore, the liquid ratio and extrudability were furtherexamined while the addition amount of the lubricant was kept at 3 wt %(to be added) and 5 wt % (to be added), at which a high extrusion ratecould be stably obtained, and the water content was changed.

[0138] Table 5 and FIG. 12 show the blend proportions (experimentalcondition) of the test product. Table 4 and FIG. 12 show also the blendproportion (experimental condition) of Example 3, too. In the diagram ofFIG. 12, the abscissa represents the addition amount of thewater-insoluble liquid lubricant in terms of wt % (to be added) and theordinate represents the water content (addition amount of water) interms of wt % (to be contained). A plurality of lines drawn slantinglyin the diagram represents the total content (liquid ratio) of water andthe water-insoluble liquid lubricant contained in the ceramic batchmaterial in terms of wt % (to be contained). The lines respectivelyrepresent from below 18.0 wt % (to be contained), 20 wt % (to becontained), 22.5 wt % (to be contained) and 24.5 wt % (to be contained).

[0139] It was found from Tables 4 and 5 that when the liquid ratio wasless than 1.0 wt % (to be contained), the clay hardness was so high (theplasticity coefficient was so great) that the extrusion pressure roseand extruding could not be carried out due to the limit of the diestrength.

[0140] It was also found that when the liquid ratio exceeded 24.5 wt %(to be contained), the clay hardness was so low (the plasticitycoefficient became so small) that shape retainability could not besecured and the ceramic honeycomb structure underwent deformation.

[0141] Particularly when a ceramic honeycomb structure having thin wallswas produced by use of a die having a small slit width, the productstrength became small and shape retainability could not be securedeasily. In addition, the die resistance increased. Therefore, the rangeof the liquid ratio in this case was at least 20.0 to 22.5 wt % (to becontained).

[0142] Incidentally, though this example represented the case ofrapeseed oil as the lubricant, substantially similar results could beobtained when other lubricants consisting of triacyl glycerin as themain component were used.

[0143]FIG. 13 shows an optimum range of water and the lubricant forproducing a ceramic honeycomb structure by combining the conditionsdescribed above with the suitable range of content of the lubricantconsisting of triacyl glycerin as the main component. This diagram hasthe same fundamental construction as that of FIG. 12, and the suitableranges of the liquid ratio and the water-insoluble liquid lubricant arehatched. TABLE 4 Condition and result of Example 3 wt % (to becontained) ratio wt % (to be added) ratio of material of materialevaluation result Experiment ceramic methyl liquid extrusion No. powdercellulose water lubricant water lubricant ratio extrudability rate ratio1 100 5.0 26.0 0.0 19.85 0.00 19.85 X 1.00 2 100 5.0 26.0 0.5 19.77 0.3820.15 ◯ 1.07 3 100 5.0 26.0 1.0 19.70 0.76 20.45 ◯ 1.54 4 100 5.0 26.01.5 19.62 1.13 20.75 ◯ 1.79 5 100 5.0 26.0 2.0 19.55 1.50 21.05 ◯ 1.88 6100 5.0 26.0 2.5 19.48 1.87 21.35 ◯ 1.91 7 100 5.0 26.0 3.0 19.40 2.2421.64 ◯ 1.93 8 100 5.0 26.0 3.5 19.33 2.60 21.93 ◯ 1.94 9 100 5.0 26.04.0 19.26 2.96 22.22 ◯ 1.95 10 100 5.0 26.0 5.0 19.12 3.68 22.79 Δ 1.9611 100 5.0 26.0 8.0 18.71 5.76 24.46 Δ 1.97 12 100 5.0 26.0 10.0 18.447.09 25.53 X 1.97

[0144] TABLE 5 Condition and result of Example 7 wt % (to be contained)ratio wt % (to be added) ratio of material of material evaluation resultExperiment ceramic methyl liquid extrusion No powder cellulose waterlubricant water lubricant ratio extrudability rate ratio 1 100 5.0 27.51.0 20.60 0.75 21.35 ◯ 1.53 2 100 5.0 26.5 2.0 19.85 1.50 21.35 ◯ 1.89 3100 5.0 25.5 3.0 19.10 2.25 21.35 ◯ 1.95 4 100 5.0 24.5 4.0 18.35 3.0021.35 ◯ 1.98 5 100 5.0 23.5 5.0 17.60 3.75 21.35 ◯ 1.99 6 100 5.0 22.56.0 16.86 4.49 21.35 ◯ 2.00 7 100 5.0 20.5 8.0 15.36 5.99 21.35 ◯ 2.01 8100 5.0 18.5 10.0 13.86 7.49 21.35 ◯ 1.99 9 100 5.0 32.0 3.0 22.86 2.1425.00 X 1.91 10 100 5.0 30.2 3.0 21.86 2.17 24.00 Δ 1.94 11 100 5.0 27.53.0 20.29 2.21 22.50 ◯ 1.95 12 100 5.0 23.3 3.0 17.71 2.29 20.00 ◯ 1.9613 100 5.0 20.8 3.0 16.17 2.33 18.50 Δ 1.93 14 100 5.0 18.5 3.0 14.632.37 17.00 X — 15 100 5.0 30.0 5.0 21.43 3.57 25.00 X 1.95 16 100 5.028.2 5.0 20.38 3.62 24.00 Δ 1.98 17 100 5.0 21.3 5.0 16.19 3.81 20.00 ◯2.00 18 100 5.0 18.8 5.0 14.62 3.88 18.50 Δ 1.99 19 100 5.0 16.5 5.013.05 3.95 17.00 X —

What is claimed is:
 1. A production method, for a ceramic structure,comprising the steps of mixing and kneading a ceramic batch materialcontaining at least ceramic powder and water, extruding the mixture sokneaded, and drying and sintering a extrudate, wherein: awater-insoluble liquid lubricant consisting of acyl glycerin as its maincomponent, and/or a derivative, is added to said ceramic batch material.2. A production method for a ceramic structure according to claim 1,wherein a viscosity of said water-insoluble liquid lubricant at 50° C.is 15 cp to 45 cp.
 3. A production method for a ceramic structureaccording to claim 1, wherein 2.0 to 8.0 wt % (to be added) of methylcellulose on the basis of 100 wt % of said ceramic powder is added tosaid ceramic bath material.
 4. A production method for a ceramicstructure according to claim 1, wherein said water-insoluble liquidlubricant consists of triacyl glycerin as a main component, and anaddition amount of said water-insoluble liquid lubricant is at least 0.5wt % (to be added) on the basis of 100 wt % of said ceramic powder.
 5. Aproduction method for a ceramic structure according to claim 4, whereina main component of an aliphatic acid constituting said triacyl glycerinis an aliphatic acid having 18 carbon atoms.
 6. A production method fora ceramic structure according to claim 4, wherein said triacyl glycerinhas a saponification value of not greater than
 200. 7. A productionmethod for a ceramic honeycomb structure having partitions arranged in ahoneycomb shape, comprising the steps of mixing and kneading a ceramicbatch material containing at least ceramic powder, water, a binder,extruding the mixture so kneaded, and drying and sintering a extrudate,wherein: a water-insoluble liquid lubricant, that is a water-insolubleliquid at a temperature of said extrusion, is added to said ceramicbatch material.
 8. A production method for a ceramic honeycomb structureaccording to claim 7, wherein a kinematic viscosity of saidwater-insoluble liquid lubricant at 20° C. is 30 cSt to 120 cSt.
 9. Aproduction method for a ceramic honeycomb structure according to claim7, wherein the sum of the contents of said water and saidwater-insoluble liquid lubricant contained in said ceramic batchmaterial is 18.0 to 24.5 wt % (to be contained) on the basis of 100 wt %of said ceramic batch material.
 10. A production method for a ceramichoneycomb structure according to claim 7, wherein said binder is methylcellulose, and the content of said binder is 2.0 to 8.0 wt % (to beadded) on the basis of 100 wt % of said ceramic powder.
 11. A productionmethod for a ceramic honeycomb structure according to claim 7, whereinthe thickness of said partition is not greater than 150 μm.
 12. Aproduction method for a ceramic honeycomb structure according to claim7, wherein said ceramic honeycomb structure is produced by extrusion byuse of a die having slits for forming said partitions, and a width ofsaid slits is not greater than 150 μm.
 13. A production method for aceramic honeycomb structure according to claim 7, wherein saidwater-insoluble liquid lubricant consists of acyl glycerin, and/or aderivative, as a main component.
 14. A production method for a ceramichoneycomb structure according to claim 7, wherein said water-insolubleliquid lubricant is triacyl glycerin, and the addition amount of saidwater-insoluble liquid lubricant is 1.0 to 8.0 wt % (to be added) on thebasis of 100 wt % of said ceramic powder.
 15. A production method for aceramic honeycomb structure according to claim 14, wherein the maincomponent of the aliphatic acid constituting said triacyl glycerin is analiphatic acid having 18 carbon atoms.
 16. A production method for aceramic honeycomb structure according to claim 14, wherein asaponification value of said triacyl glycerin is not greater than 200.